The IA DjVus are great. They are encoded with a background separation method called MRC (mixed raster content), and they used a proprietary compressor to do it.

The IA DjVus are great. They are encoded with a background separation method called MRC (mixed raster content), and they used a proprietary compressor to do it. The PDFs do the same thing, but they use JPEG2000, which is incredibly slow (10 seconds per page on an weedy ereader application processor). Sadly, the IA stopped making DjVus years ago, so anything scanned recently is incredibly painful to read on a mobile device.